The invention has been developed primarily in relation to a clamping device which can be used to hold-down metal grids (or gratings) on support beams, such grids being of the type which can be used as decking, and particularly for marine use e.g. on oil and gas drilling platforms. Grids of this type are useful as decking in a marine environment, in that they can provide a sufficiently strong support surface, and yet can readily permit any water which falls on the decking to drain away by gravity through the spaces which are defined between the generally elongate elements or "bars" of the grid.
It is well known to use various types of clamping device in order to secure or hold-down grids onto structural beams of a supporting structure. The lateral gaps between adjacent bars of grids are often relatively narrow, so that it can be a difficult task, with existing construction of clamping device or "fastener", to install and to tighten the device. Thus, the lower part of the device has to be passed downwardly through the space, and then has to be manipulated so as to make initial engagement with a part of an underlying support beam. Thereafter, the device has to be tightened, and in such a way that the lower part does not decome disengaged from the underlying support beam. It is a common experience, with many existing types of fastener, that an initial "hold" of a lower engaging part becomes disengaged when initial tightening of the fastener takes place.
Therefore, and particularly bearing in mind the arduous operating conditions which are liable to occur during the installation of decking on drilling rigs or platforms, there is a clear need to provide an improved design of clamping device for holding-down a grid on a support beam (e.g. for use as decking), in which the initial installation of the device, and the subsequent tightening, can be carried out readily and without undue manipulation, and in which the entire operation can be carried out from one side of the grid (usually the upper side), without the operator having to insert his hand or fingers through the space between two bars of the grid in order to hold and/or manipulate the lower part of the clamping device.